Elbow for cabin air flow system

ABSTRACT

An elbow for use in a cabin air supply system for an aircraft has an inlet duct. The inlet duct diverges into two outlet ducts with an interface area between the outlet ducts. Each of the outlet ducts has a nominal wall thickness, with a central portion of the interface having a first thickness at a point of maximum thickness, and the nominal wall thickness being of a second thickness. The central portion of the interface curves to the central portion of the interface area. A ratio of the first thickness to the second thickness is between 3 and 8. A cabin air supply system is also disclosed.

BACKGROUND OF THE INVENTION

This application relates to a fluid elbow for communicating a source of compressed air to outlets, which are part of an air supply system for an aircraft cabin.

Aircraft cabins are provided with a source of heated air, typically from an air compressor. In one such system the air compressor delivers air into an inlet of an elbow, and the elbow has two outlets. Each outlet leads to a trim valve, which in turn controls the flow of the heated air to ducts within the aircraft cabin.

As with all components on an aircraft, it is desirable to reduce the weight of the elbow. Thus, the elbow is provided with relatively thin walls.

SUMMARY

An elbow for use in a cabin air supply system for an aircraft has an inlet duct. The inlet duct diverges into two outlet ducts with an interface area between the outlet ducts. Each of the outlet ducts has a nominal wall thickness, with a central portion of the interface having a first thickness at a point of maximum thickness, and the nominal wall thickness being of a second thickness. The central portion of the interface curves to the central portion of the interface area. A ratio of the first thickness to the second thickness is between 3 and 8. A cabin air supply system is also disclosed.

These and other features of this application will be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a cabin air supply system for an aircraft.

FIG. 2 shows an elbow associated with the FIG. 1 system.

FIG. 3 shows a detail of the FIG. 2 elbow.

DETAILED DESCRIPTION

A cabin air supply system 20 is illustrated in FIG. 1. An air compressor 22 compresses air and delivers into an elbow 24 at an inlet duct 26. The elbow 24 is formed of aluminum. The inlet duct 26 communicates with a first outlet duct 28 which delivers air to trim valve 30, which controls the supply of air to a duct 32. Duct 32 provides heated air into a portion of an aircraft cabin. A second outlet duct 34 delivers heated air to a trim valve 36 and a duct 38. An interface area 39 between outlets 28 and 34 is particularly challenging to design. Applicant has discovered there are stresses and challenges on the interface area that do not suggest the thin walls used elsewhere on the elbows be used.

As shown in FIG. 2, interface area 39 is provided with a thicker central portion 52. Central portion 52 is thicker than the nominal wall thickness 50 of the duct leading to the outlets 34 and 28. In one embodiment, the inlet duct 36 had a diameter D₁, the outlet duct 34 had a diameter D₂, and the outlet duct 28 had the same diameter D₂.

In this embodiment D₁ was 2.78 inch (7.06 centimeter) and D₂ was 2.78 inch (7.06 centimeter).

As shown in FIG. 3, the central portion 52 has a wall thickness d₁ , while a nominal wall thickness at 50 is d₂. Notably, the central portion wall thickness is not a constant and varies continuously from the nominal wall thickness near the inlet to the maximum in the region shown). In one embodiment, d₁ was 0.5 inch (1.27 centimeter), and d₂ was 0.11 inch (0.28 centimeter). As also shown, the sides 54 of the thicker interface 39 curve upwardly to the thickest central portion 52.

Also, an outer face of the interface area 39 is formed on a radius R₁. In this same embodiment R₁ was 0.75 inch (1.905 centimeter). A radius R₂ on the opposite side was 0.26 inch (0.66 cm)

In embodiments, a ratio of the maximum d₁ to d₂ was between 3 and 8. A ratio of d₁ to R₁ was between 0.5 and 0.9. A ratio of D₂ to d₁ was between 4 and 7. A ratio of R₁ to R₂ was between 2.4 and 3.4.

Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention. 

1. An elbow for use in a cabin air supply system for an aircraft comprising: an inlet duct diverging into two outlet ducts with an interface area between said outlet ducts; and a nominal wall thickness between said interface area and said outlet ducts, with a central portion of said interface area having a first thickness at a point of maximum thickness, and said nominal wall thickness being of a second thickness, and wherein said interface area curving to said central portion of said interface area, and a ratio of said first thickness to said second thickness being between 3 and
 8. 2. The elbow as set forth in claim 1, wherein said outlet ducts having a first diameter, and a ratio of said first diameter to said first thickness being between 4 and
 7. 3. The elbow as set forth in claim 2, wherein an outer face of said central portion of said interface area is formed at a first radius of curvature, and a ratio of said first thickness to said first radius of curvature is between 0.5 and 0.9.
 4. The elbow as set forth in claim 3, wherein said first radius of curvature to a radius of curvature on an inner face of said inner face area is between 2.4 and 3.4.
 5. The elbow as set forth in claim 1, wherein said elbow is formed of aluminum.
 6. A cabin air supply system comprising: a cabin air compressor delivering air into an inlet duct of an elbow, and said elbow having two outlet ducts, with each of said outlet ducts communicating to trim valves, with said trim valves selectively supplying air to ducts to be positioned in an aircraft cabin; said inlet duct diverging into said two outlet ducts with an interface area section between said outlet ducts; and a nominal wall thickness between said interface area and said outlet ducts, with a central portion of said interface area having a first thickness at a point of maximum thickness, and said nominal wall thickness being of a second thickness, and wherein said interface area curving to said central portion of said interface area, and a ratio of said first thickness to said second thickness being between 3 and
 8. 7. The cabin air supply system as set forth in claim 6, wherein said outlet duct having a first diameter, and a ratio of said first diameter to said first thickness being between 4 and
 7. 8. The cabin air supply system as set forth in claim 7, wherein an outer face of said central portion of said interface area is formed at a first radius of curvature and a ratio of said first thickness to said first radius of curvature is between 0.5 and 0.9.
 9. The cabin air supply system as set forth in claim 8, wherein said first radius of curvature to a radius of curvature on an inner face of said inner face area is between 2.4 and 3.4.
 10. The cabin air supply system as set forth in claim 6, wherein said elbow is formed of aluminum.
 11. An elbow for use in a cabin air supply system for an aircraft comprising: an inlet duct diverging into two outlet ducts with an interface area between said outlet ducts; a nominal wall thickness between said interface area and said outlet ducts, with a central portion of said interface area having a first thickness at a point of maximum thickness, and said nominal wall thickness being of a second thickness, and wherein said interface area curving to said central portion of said interface area, and a ratio of said first thickness to said second thickness being between 3 and 8; said outlet duct having a first diameter, and a ratio of said first diameter to said first thickness being between 4 and 7; an outer face of said central portion of said interface area is formed at a first radius of curvature, and a ratio of said first thickness to said first ratio of curvature is between 0.5 and 0.9; and said elbow formed of aluminum. 